Like other inventors, Isaac Merritt Singer did not invent the machine that made him famous. He improved on previous designs and completely changed how big ticket items were purchased, allowing for more people than ever before to afford their own sewing machine. Singer changed the design of the sewing machine to allow the shuttle to run in a straight line, and made the needle straight and vertical (it was originally curved and horizontal). Most of the machine was built of iron, making it incredibly heavy. The Singer sewing machine’s success was not due to the invention itself, but the way it was sold, because for the first time payment plans were offered to customers, and to the company’s astonishment, they found people would pay $100 in $5 monthly installments, instead of $50 outright. Another key sales concept was convincing customers that women could operate the machines themselves at a time when many machines were seen as too heavy and difficult for “delicate” ladies to operate.